An X-ray diagnosis apparatus irradiates a subject with X-rays and detects the intensity of X-rays that have passed through the subject to display an image of the internal structure of the subject.
The X-ray diagnosis apparatus is provided with a light source device. In X-ray diagnosis, an operator checks the X-ray irradiation field by visually checking the irradiation field of light from the light source device. The light source device is located in an X-ray irradiation unit such that the optical path of X-rays and that of light emitted therefrom are combined together.
A halogen lamp is used for the conventional light source device. The light source device has a short service life. In addition, although being a light source that simulates an X-ray focal point, the halogen lamp cannot be regarded as a point light source having a sufficiently small light emission point. Therefore, the boundary of the light irradiation field is not clear, and the operator finds it difficult to identify the irradiation field.
Besides, a plurality of light-emitting semiconductors are required to emit light of sufficient brightness when they are used as a substitute for the halogen lamp because of their long service life. However, the plural light-emitting semiconductors do not provide a point light source. Further, the light irradiation field suffers from non-uniform brightness. For these reasons, it is also difficult in this case to identify the irradiation field.
Because of the short service life and poor time response of the halogen lamp, the operator has difficulty in knowing the operating state of the X-ray diagnosis apparatus while viewing the light of the irradiation field.